Devices and methods to use power spectrum or signal association for pain management

ABSTRACT

Methods and systems for electrical stimulation can include obtaining a biosignal of the patient; altering at least one stimulation parameter of an electrical stimulation system in response to the biosignal; and delivering an electrical stimulation current to one or more selected electrodes of the electrical stimulation system using the at least one stimulation parameter. In some embodiments, a power spectrum is determined from the biosignal. In some embodiments, the biosignal is at least two different biosignals measured at the same or different locations on the patient and a coherence, correlation, or association between the two biosignal is determined.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/138,381, filed Sep. 21, 2018, which is a continuation of U.S. patentapplication Ser. No. 15/890,008, filed Feb. 6, 2018, which issued asU.S. Pat. No. 10,130,816, which is a continuation of U.S. patentapplication Ser. No. 14/861,524, filed Sep. 22, 2015, which issued asU.S. Pat. No. 9,925,378, and which claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No. 62/053,427, filedSep. 22, 2014, all of which are incorporated herein by reference.

FIELD

The present invention is directed to the area of implantable electricalstimulation systems and methods of making and using the systems. Thepresent invention is also directed to implantable electrical stimulationsystems that use a measured power spectrum or signal coherence or othermeasure of association to modify or alter stimulation parameters, aswell as methods of making and using the leads and electrical stimulationsystems.

BACKGROUND

Implantable electrical stimulation systems have proven therapeutic in avariety of diseases and disorders. For example, spinal cord stimulationsystems have been used as a therapeutic modality for the treatment ofchronic pain syndromes. Peripheral nerve stimulation has been used totreat chronic pain syndrome and incontinence, with a number of otherapplications under investigation. Functional electrical stimulationsystems have been applied to restore some functionality to paralyzedextremities in spinal cord injury patients.

Stimulators have been developed to provide therapy for a variety oftreatments. A stimulator can include a control module (with a pulsegenerator), one or more leads, and an array of stimulator electrodes oneach lead. The stimulator electrodes are in contact with or near thenerves, muscles, or other tissue to be stimulated. The pulse generatorin the control module generates electrical pulses that are delivered bythe electrodes to body tissue.

BRIEF SUMMARY

One embodiment is a non-transitory computer-readable medium havingprocessor-executable instructions for adjusting stimulation parametersof an electrical stimulation system including a control module implantedin a patient, the processor-executable instructions when installed ontoa device enable the device to perform actions. The actions includeobtaining a biosignal of the patient; and altering at least onestimulation parameter of an electrical stimulation system in response tothe biosignal.

In at least some embodiments, the actions further include delivering anelectrical stimulation current to one or more selected electrodes of theelectrical stimulation system using the at least one stimulationparameter. In at least some embodiments, the actions further includecommunicating the at least one stimulation parameter to an implantablecontrol module. In at least some embodiments, the actions furtherinclude determining a power spectrum from the biosignal, where alteringat least one stimulation parameter includes altering at least onestimulation parameter of the electrical stimulation system in responseto the power spectrum. In at least some embodiments, the actions furtherinclude repeating the obtaining, altering and delivering actions atleast once.

In at least some embodiments, the biosignal is at least two differentbiosignals and the actions further include determining a coherence,correlation, or association between the at least two differentbiosignals, where altering at least one stimulation parameter includesaltering at least one stimulation parameter of the electricalstimulation system in response to the coherence, correlation, orassociation between the at least two different biosignals.

In at least some embodiments, the biosignal includes at least one bandof an electroencephalograph of the patient. In at least someembodiments, the at least one band is a theta band.

Another embodiment is an electrical stimulation system that includes animplantable control module for implantation in a body of a patient andhaving an antenna and a processor coupled to the antenna. The controlmodule is configured and arranged to provide electrical stimulationsignals to an electrical stimulation lead coupled to the implantablecontrol module for stimulation of patient tissue. The system alsoincludes an external programming unit configured and arranged tocommunicate with the processor of the implantable control module usingthe antenna and to adjust stimulation parameters for production of theelectrical stimulation signals. The external programming unit includes auser interface configured and arranged to receive input from a user, anda processor in communication with the user interface and configured andarranged to perform the following actions: obtaining a biosignal of thepatient; altering at least one stimulation parameter of an electricalstimulation system in response to the biosignal; and communicating theat least one stimulation parameter to the implantable control module.

Yet another embodiment is an electrical stimulation system including animplantable control module configured and arranged for implantation in abody of a patient. The control module is configured and arranged toprovide electrical stimulation signals to an electrical stimulation leadcoupled to the implantable control module for stimulation of patienttissue. The implantable control module includes an antenna configuredand arranged to receive input, and a processor in communication with theantenna and configured and arranged to perform the following actions:obtaining a biosignal of the patient via the antenna; altering at leastone stimulation parameter of an electrical stimulation system inresponse to the biosignal; and delivering an electrical stimulationcurrent to one or more selected electrodes of the electrical stimulationsystem using that at least one stimulation parameter.

In at least some embodiments, any of the systems can include at leastone sensor configured and arranged to obtain the biosignal of thepatient. In at least some embodiments, in any of the systems the actionsfurther include determining a power spectrum from the biosignal, wherealtering at least one stimulation parameter comprises altering at leastone stimulation parameter of the electrical stimulation system inresponse to the power spectrum. In at least some embodiments, in any ofthe systems the biosignal is at least two different biosignals and theactions further include determining a coherence, correlation, orassociation between the at least two different biosignals, wherealtering at least one stimulation parameter comprises altering at leastone stimulation parameter of the electrical stimulation system inresponse to the coherence, correlation, or association between the atleast two different biosignals.

In at least some embodiments, any of the systems can include anelectrical stimulation lead coupleable to the implantable control moduleand comprising a plurality of electrodes disposed along a distal endportion of the electrical stimulation lead. In at least someembodiments, in any of the systems the biosignal is at least one band ofan electroencephalograph of the patient, wherein the at least one bandis a theta band.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present invention aredescribed with reference to the following drawings. In the drawings,like reference numerals refer to like parts throughout the variousfigures unless otherwise specified.

For a better understanding of the present invention, reference will bemade to the following Detailed Description, which is to be read inassociation with the accompanying drawings, wherein:

FIG. 1 is a schematic view of one embodiment of an electricalstimulation system that includes a paddle lead electrically coupled to acontrol module, according to the invention;

FIG. 2 is a schematic view of one embodiment of an electricalstimulation system that includes a percutaneous lead electricallycoupled to a control module, according to the invention;

FIG. 3A is a schematic view of one embodiment of the control module ofFIG. 1 configured and arranged to electrically couple to an elongateddevice, according to the invention;

FIG. 3B is a schematic view of one embodiment of a lead extensionconfigured and arranged to electrically couple the elongated device ofFIG. 2 to the control module of FIG. 1, according to the invention;

FIG. 4 is a schematic block diagram of one embodiment of an electricalstimulation system, according to the invention;

FIG. 5 is a schematic block diagram of one embodiment of an externalprogramming unit, according to the invention;

FIG. 6 is a flowchart of one embodiment of a method for adjustingstimulation parameters, according to the invention;

FIG. 7 is a flowchart of another embodiment of a method for adjustingstimulation parameters, according to the invention;

FIG. 8 is a flowchart of a further embodiment of a method for adjustingstimulation parameters, according to the invention; and

FIG. 9 is a flowchart of yet another embodiment of a method foradjusting stimulation parameters, according to the invention.

DETAILED DESCRIPTION

The present invention is directed to the area of implantable electricalstimulation systems and methods of making and using the systems. Thepresent invention is also directed to implantable electrical stimulationsystems that use a measured power spectrum or signal coherence or othermeasure of association to modify or alter stimulation parameters, aswell as methods of making and using the leads and electrical stimulationsystems.

Suitable implantable electrical stimulation systems include, but are notlimited to, a least one lead with one or more electrodes disposed alonga distal end of the lead and one or more terminals disposed along theone or more proximal ends of the lead. Leads include, for example,percutaneous leads, paddle leads, and cuff leads. Examples of electricalstimulation systems with leads are found in, for example, U.S. Pat. Nos.6,181,969; 6,516,227; 6,609,029; 6,609,032; 6,741,892; 7,949,395;7,244,150; 7,672,734; 7,761,165; 7,974,706; 8,175,710; 8,224,450; and8,364,278; and U.S. Patent Application Publication No. 2007/0150036, allof which are incorporated by reference.

FIG. 1 illustrates schematically one embodiment of an electricalstimulation system 100. The electrical stimulation system includes acontrol module (e.g., a stimulator or pulse generator) 102 and a lead103 coupleable to the control module 102. The lead 103 includes a paddlebody 104 and one or more lead bodies 106. In FIG. 1, the lead 103 isshown having two lead bodies 106. It will be understood that the lead103 can include any suitable number of lead bodies including, forexample, one, two, three, four, five, six, seven, eight or more leadbodies 106. An array 133 of electrodes, such as electrode 134, isdisposed on the paddle body 104, and an array of terminals (e.g., 310 inFIG. 3A-3B) is disposed along each of the one or more lead bodies 106.

It will be understood that the electrical stimulation system can includemore, fewer, or different components and can have a variety of differentconfigurations including those configurations disclosed in theelectrical stimulation system references cited herein. For example,instead of a paddle body, the electrodes can be disposed in an array ator near the distal end of a lead body forming a percutaneous lead.

FIG. 2 illustrates schematically another embodiment of the electricalstimulation system 100, where the lead 103 is a percutaneous lead. InFIG. 2, the electrodes 134 are shown disposed along the one or more leadbodies 106. In at least some embodiments, the lead 103 is isodiametricalong a longitudinal length of the lead body 106.

The lead 103 can be coupled to the control module 102 in any suitablemanner. In FIG. 1, the lead 103 is shown coupling directly to thecontrol module 102. In at least some other embodiments, the lead 103couples to the control module 102 via one or more intermediate devices(324 in FIG. 3B). For example, in at least some embodiments one or morelead extensions 324 (see e.g., FIG. 3B) can be disposed between the lead103 and the control module 102 to extend the distance between the lead103 and the control module 102. Other intermediate devices may be usedin addition to, or in lieu of, one or more lead extensions including,for example, a splitter, an adaptor, or the like or combinationsthereof. It will be understood that, in the case where the electricalstimulation system 100 includes multiple elongated devices disposedbetween the lead 103 and the control module 102, the intermediatedevices may be configured into any suitable arrangement.

In FIG. 2, the electrical stimulation system 100 is shown having asplitter 107 configured and arranged for facilitating coupling of thelead 103 to the control module 102. The splitter 107 includes a splitterconnector 108 configured to couple to a proximal end of the lead 103,and one or more splitter tails 109 a and 109 b configured and arrangedto couple to the control module 102 (or another splitter, a leadextension, an adaptor, or the like).

With reference to FIGS. 1 and 2, the control module 102 typicallyincludes a connector housing 112 and a sealed electronics housing 114.An electronic subassembly 110 and an optional power source 120 aredisposed in the electronics housing 114. A control module connector 144is disposed in the connector housing 112. The control module connector144 is configured and arranged to make an electrical connection betweenthe lead 103 and the electronic subassembly 110 of the control module102.

The electrical stimulation system or components of the electricalstimulation system, including the paddle body 104, the one or more ofthe lead bodies 106, and the control module 102, are typically implantedinto the body of a patient. The electrical stimulation system can beused for a variety of applications including, but not limited to deepbrain stimulation, neural stimulation, spinal cord stimulation, musclestimulation, and the like.

The electrodes 134 can be formed using any conductive, biocompatiblematerial. Examples of suitable materials include metals, alloys,conductive polymers, conductive carbon, and the like, as well ascombinations thereof. In at least some embodiments, one or more of theelectrodes 134 are formed from one or more of: platinum, platinumiridium, palladium, palladium rhodium, or titanium.

Any suitable number of electrodes 134 can be disposed on the leadincluding, for example, four, five, six, seven, eight, nine, ten,eleven, twelve, fourteen, sixteen, twenty-four, thirty-two, or moreelectrodes 134. In the case of paddle leads, the electrodes 134 can bedisposed on the paddle body 104 in any suitable arrangement. In FIG. 1,the electrodes 134 are arranged into two columns, where each column haseight electrodes 134.

The electrodes of the paddle body 104 (or one or more lead bodies 106)are typically disposed in, or separated by, a non-conductive,biocompatible material such as, for example, silicone, polyurethane,polyetheretherketone (“PEEK”), epoxy, and the like or combinationsthereof. The one or more lead bodies 106 and, if applicable, the paddlebody 104 may be formed in the desired shape by any process including,for example, molding (including injection molding), casting, and thelike. The non-conductive material typically extends from the distal endsof the one or more lead bodies 106 to the proximal end of each of theone or more lead bodies 106.

In the case of paddle leads, the non-conductive material typicallyextends from the paddle body 104 to the proximal end of each of the oneor more lead bodies 106. Additionally, the non-conductive, biocompatiblematerial of the paddle body 104 and the one or more lead bodies 106 maybe the same or different. Moreover, the paddle body 104 and the one ormore lead bodies 106 may be a unitary structure or can be formed as twoseparate structures that are permanently or detachably coupled together.

Terminals (e.g., 310 in FIGS. 3A-3B) are typically disposed along theproximal end of the one or more lead bodies 106 of the electricalstimulation system 100 (as well as any splitters, lead extensions,adaptors, or the like) for electrical connection to correspondingconnector contacts (e.g., 314 in FIG. 3A). The connector contacts aredisposed in connectors (e.g., 144 in FIGS. 1-3B; and 322 FIG. 3B) which,in turn, are disposed on, for example, the control module 102 (or a leadextension, a splitter, an adaptor, or the like). Electrically conductivewires, cables, or the like (not shown) extend from the terminals to theelectrodes 134. Typically, one or more electrodes 134 are electricallycoupled to each terminal. In at least some embodiments, each terminal isonly connected to one electrode 134.

The electrically conductive wires (“conductors”) may be embedded in thenon-conductive material of the lead body 106 or can be disposed in oneor more lumens (not shown) extending along the lead body 106. In someembodiments, there is an individual lumen for each conductor. In otherembodiments, two or more conductors extend through a lumen. There mayalso be one or more lumens (not shown) that open at, or near, theproximal end of the one or more lead bodies 106, for example, forinserting a stylet to facilitate placement of the one or more leadbodies 106 within a body of a patient. Additionally, there may be one ormore lumens (not shown) that open at, or near, the distal end of the oneor more lead bodies 106, for example, for infusion of drugs ormedication into the site of implantation of the one or more lead bodies106. In at least one embodiment, the one or more lumens are flushedcontinually, or on a regular basis, with saline, epidural fluid, or thelike. In at least some embodiments, the one or more lumens arepermanently or removably sealable at the distal end.

FIG. 3A is a schematic side view of one embodiment of a proximal end ofone or more elongated devices 300 configured and arranged for couplingto one embodiment of the control module connector 144. The one or moreelongated devices may include, for example, one or more of the leadbodies 106 of FIG. 1, one or more intermediate devices (e.g., asplitter, the lead extension 324 of FIG. 3B, an adaptor, or the like orcombinations thereof), or a combination thereof.

The control module connector 144 defines at least one port into which aproximal end of the elongated device 300 can be inserted, as shown bydirectional arrows 312 a and 312 b. In FIG. 3A (and in other figures),the connector housing 112 is shown having two ports 304 a and 304 b. Theconnector housing 112 can define any suitable number of ports including,for example, one, two, three, four, five, six, seven, eight, or moreports.

The control module connector 144 also includes a plurality of connectorcontacts, such as connector contact 314, disposed within each port 304 aand 304 b. When the elongated device 300 is inserted into the ports 304a and 304 b, the connector contacts 314 can be aligned with a pluralityof terminals 310 disposed along the proximal end(s) of the elongateddevice(s) 300 to electrically couple the control module 102 to theelectrodes (134 of FIG. 1) disposed on the paddle body 104 of the lead103. Examples of connectors in control modules are found in, forexample, U.S. Pat. Nos. 7,244,150 and 8,224,450, which are incorporatedby reference.

FIG. 3B is a schematic side view of another embodiment of the electricalstimulation system 100. The electrical stimulation system 100 includes alead extension 324 that is configured and arranged to couple one or moreelongated devices 300 (e.g., one of the lead bodies 106 of FIGS. 1 and2, the splitter 107 of FIG. 2, an adaptor, another lead extension, orthe like or combinations thereof) to the control module 102. In FIG. 3B,the lead extension 324 is shown coupled to a single port 304 defined inthe control module connector 144. Additionally, the lead extension 324is shown configured and arranged to couple to a single elongated device300. In alternate embodiments, the lead extension 324 is configured andarranged to couple to multiple ports 304 defined in the control moduleconnector 144, or to receive multiple elongated devices 300, or both.

A lead extension connector 322 is disposed on the lead extension 324. InFIG. 3B, the lead extension connector 322 is shown disposed at a distalend 326 of the lead extension 324. The lead extension connector 322includes a connector housing 328. The connector housing 328 defines atleast one port 330 into which terminals 310 of the elongated device 300can be inserted, as shown by directional arrow 338. The connectorhousing 328 also includes a plurality of connector contacts, such asconnector contacts 340. When the elongated device 300 is inserted intothe port 330, the connector contacts 340 disposed in the connectorhousing 328 can be aligned with the terminals 310 of the elongateddevice 300 to electrically couple the lead extension 324 to theelectrodes (134 of FIGS. 1 and 2) disposed along the lead (103 in FIGS.1 and 2).

In at least some embodiments, the proximal end of the lead extension 324is similarly configured and arranged as a proximal end of the lead 103(or other elongated device 300). The lead extension 324 may include aplurality of electrically conductive wires (not shown) that electricallycouple the connector contacts 340 to a proximal end 348 of the leadextension 324 that is opposite to the distal end 326. In at least someembodiments, the conductive wires disposed in the lead extension 324 canbe electrically coupled to a plurality of terminals (not shown) disposedalong the proximal end 348 of the lead extension 324. In at least someembodiments, the proximal end 348 of the lead extension 324 isconfigured and arranged for insertion into a connector disposed inanother lead extension (or another intermediate device). In otherembodiments (and as shown in FIG. 3B), the proximal end 348 of the leadextension 324 is configured and arranged for insertion into the controlmodule connector 144.

It is known that brain waves and other waves can adopt oscillatorypatterns within a number of different frequency bands. For example,brain wave bands have been detected as biosignals using EEG and othermethods and have been designated as, for example, delta, theta, alpha,beta, and gamma bands and the like. It at least some instancesparticular frequencies or frequency ranges within these bands can beindicative of abnormal conditions. As an example, it has been found thatpain signals can be associated with frequencies in the theta band(approximately 4-8 Hz) that are shifted in frequency from a normal,“pain-free” frequency or frequency range within that band.

Although not wishing to be bound by any particular theory, it is thoughtthat observing one or more of these frequency bands or portions of thefrequency bands can indicate efficacy of treatment and can be used toadjust stimulation parameters. Other biosignals can also be observed andused to adjust stimulation parameters. In at least some embodiments, thepower spectrum of a biosignal can be determined and used to adjuststimulation parameters. The power spectrum displays signal power as afunction of frequency. The determination of a power spectrum from atime-varying signal, such as a biosignal, is well known and can include,for example, Fourier transformation of the biosignal or the like. In atleast some embodiments, the theta band (4-8 Hz) or a portion of thetheta band is observed and a power spectrum is calculated. One or morestimulation parameters can then be adjusted based on the power spectrumto enhance or improve the efficacy of the electrical stimulation.

Additionally or alternatively, two different biosignals can be measuredand the coherence, correlation, or any other measure of associationbetween the two biosignals can be determined. The two differentbiosignals can be, for example, the same type of biosignal measured attwo different locations on the patient's body or two different types ofbiosignals measured at the same or different locations on the patient'sbody. As one example of the latter case, the two different types ofbiosignals can be 1) an EEG of the theta band and 2) an EEG of the gammaband. It will also be understood that more than two biosignals (forexample, three, four, or more biosignals) can be measured and thecoherence, correlation, or any other measure of association between thebiosignals can be determined. Other measures of association can include,but are not limited to, power spectrum (a spectrum is a Fouriertransform of the auto-correlation and can be a measure of association ofa signal at one time point with the same signal at another time point),phase-amplitude coupling, bicoherence, or the like.

The existence of coherence, correlation, or other association betweentwo or more different biosignals can be indicative of synchronousactivity which can be indicative or pain or other abnormal conditionthat is transmitted along the neural tissue. The determination ofcoherence, correlation, or association between two or more signals iswell-known and can be implemented for the biosignals. In at least someembodiments, the theta band (4-8 Hz) or a portion of the theta band isobserved at two different locations and coherence, correlation, orassociation between the two or more biosignals is calculated. In atleast some embodiments, the theta band (4-8 Hz) or the gamma band (25-90Hz) may be acquired at the same location or different locations andcoherence or correlation or other measure of association between the twobiosignals is calculated. One or more stimulation parameters can then beadjusted based on the coherence, correlation, or association to enhanceor improve the efficacy of the electrical stimulation. Additionalexamples of stimulation at two different stimulation sites todesynchronize synchronous activity can be found in U.S. ProvisionalPatent Application Ser. No. 62/053,589, filed on even date herewith(Attorney Docket No. BSNC-1-368.0).

In at least some embodiments, the determination of either the powerspectrum of a biosignal or the association (e.g., coherence,correlation, or the like) between two or more biosignals followed by theadjustment of stimulation parameters can be used in a feedback loopduring a system programming session to select final stimulationparameters. For example, an external programming unit can providestimulation parameters to a control module which generates theelectrical stimulation. One or more sensors can then be used to obtainthe biosignal(s) and the power spectrum or association (e.g., coherence,correlation, or the like) can then be determined. This information canbe provided to a user or to the external programming unit and thestimulation parameters can be adjusted manually or automatically inresponse.

In at least some embodiments, the determination of either the powerspectrum of a biosignal or the association (e.g., coherence,correlation, or the like) between two or more biosignals followed by theadjustment of stimulation parameters and the adjustment of stimulationparameters can be used in a feedback loop during system operation toadjust stimulation parameters to improve the efficacy of stimulation.For example, a control module generates the electrical stimulation usinga set of stimulation parameters. One or more sensors can then be used toobtain the biosignal(s) and the power spectrum or association (e.g.,coherence, correlation, or the like) can then be determined. Thisinformation can be provided to the control module (optionally, thecontrol module can determine the power spectrum or association (e.g.,coherence, correlation, or the like) using the biosignal(s) from thesensor(s)) and the stimulation parameters can be adjusted automaticallyin response.

An electrical stimulation system includes a stimulator (for example, acontrol module/lead or a microstimulator). Any suitable stimulationsystem can be used including those described in the reference citedabove. FIG. 4 illustrates schematically one embodiment of an electricalstimulation system 400 that includes an implantable control module(e.g., an implantable electrical stimulator or implantable pulsegenerator) 402, one or more leads 408 with electrodes, one or moreexternal programming units 406, and one or more sensors 405.Alternatively, the implantable control module 402 can be part of amicrostimulator with the electrodes disposed on the housing of themicrostimulator. The microstimulator may not include a lead or, in otherembodiments, a lead may extend from the microstimulator. It will beunderstood that the electrical stimulation system can include more,fewer, or different components and can have a variety of differentconfigurations including those configurations disclosed in thereferences cited herein.

The lead 408 is coupled, or coupleable, to the implantable controlmodule 402. The implantable control module 402 includes a processor 410,an antenna 412 (or other communications arrangement), a power source414, and a memory 416, as illustrated in FIG. 4.

An external programming unit 406 can include, for example, a processor450, a memory 452, a communications arrangement 454 (such as an antennaor any other suitable communications device such as those describedbelow), and a user interface 456, as illustrated in FIG. 5. Suitabledevices for use as an external programming unit can include, but are notlimited to, a computer, a tablet, a mobile telephone, a personal deskassistant, a dedicated device for external programming, remote control,or the like. It will be understood that the external programming unit406 can include a power supply or receive power from an external sourceor any combination thereof. In at least some embodiments, the externalprogramming unit 406 may also be a patient interface unit.

The one or more sensors 405 can be any suitable sensors for measuring abiosignal. Examples of biosignals include EEG, electrocochleograph(ECOG), heart rate, ECG, blood pressure, electrical signals traversingthe spinal cord or a nerve or group of nerves, and the like. Any sensorsuitable for measuring the corresponding biosignal can be used. Thesensor can be implanted or positioned on the body of the patient. Insome embodiments, at least one sensor is provided on the lead and canbe, for example, a separate recording electrode for recording electricalsignals or can be one or more stimulating electrodes that also are usedfor recording electrical signals. The sensor 405 can be in communicationwith the external programming unit 406 of the control module 402 orboth. Such communication can be wired or wireless or any combinationthereof using any of the methods described below. In at least someembodiments, the sensor 405 is deployed and used only during aprogramming session. In other embodiments, the sensor 405 may bedeployed on or within the patient and in regular or constantcommunication with the control module 402.

Methods of communication between devices or components of a system caninclude wired or wireless (e.g., RF, optical, infrared, near fieldcommunication (NFC), Bluetooth™, or the like) communications methods orany combination thereof. By way of further example, communicationmethods can be performed using any type of communication media or anycombination of communication media including, but not limited to, wiredmedia such as twisted pair, coaxial cable, fiber optics, wave guides,and other wired media and wireless media such as acoustic, RF, optical,infrared, NFC, Bluetooth™ and other wireless media. These communicationmedia can be used for communications arrangements in the externalprogramming unit 406 or in the sensor 405 or as antenna 412 or as analternative or supplement to antenna 412.

Turning to the control module 402, some of the components (for example,a power source 414, an antenna 412, and a processor 410) of theelectrical stimulation system can be positioned on one or more circuitboards or similar carriers within a sealed housing of the control module(implantable pulse generator,) if desired. Any power source 414 can beused including, for example, a battery such as a primary battery or arechargeable battery. Examples of other power sources include supercapacitors, nuclear or atomic batteries, mechanical resonators, infraredcollectors, thermally-powered energy sources, flexural powered energysources, bioenergy power sources, fuel cells, bioelectric cells, osmoticpressure pumps, and the like including the power sources described inU.S. Pat. No. 7,437,193, incorporated herein by reference.

As another alternative, power can be supplied by an external powersource through inductive coupling via the antenna 412 or a secondaryantenna. The external power source can be in a device that is mounted onthe skin of the user or in a unit that is provided near the user on apermanent or periodic basis.

If the power source 414 is a rechargeable battery, the battery may berecharged using the antenna 412, if desired. Power can be provided tothe battery for recharging by inductively coupling the battery throughthe antenna to a recharging unit external to the user.

A stimulation signal, such as electrical current in the form ofelectrical pulses, is emitted by the electrodes of the lead 408 (or amicrostimulator) to stimulate neurons, nerve fibers, muscle fibers, orother body tissues near the electrical stimulation system. Examples ofleads are described in more detail below. The processor 410 is generallyincluded to control the timing and electrical characteristics of theelectrical stimulation system. For example, the processor 410 can, ifdesired, control one or more of the timing, frequency, strength,duration, and waveform of the pulses. In addition, the processor 410 canselect which electrodes can be used to provide stimulation, if desired.In some embodiments, the processor 410 selects which electrode(s) arecathodes and which electrode(s) are anodes. In some embodiments, theprocessor 410 is used to identify which electrodes provide the mostuseful stimulation of the desired tissue.

With respect to the control module 402 and external programming unit406, any suitable processor 410, 450 can be used in these devices. Forthe control module 402, the processor 410 is capable of receiving andinterpreting instructions from an external programming unit 406 that,for example, allows modification of pulse characteristics. In theillustrated embodiment, the processor 410 is coupled to the antenna 412.This allows the processor 410 to receive instructions from the externalprogramming unit 406 to, for example, direct the pulse characteristicsand the selection of electrodes, if desired. The antenna 412, or anyother antenna described herein, can have any suitable configurationincluding, but not limited to, a coil, looped, or looplessconfiguration, or the like.

In one embodiment, the antenna 412 is capable of receiving signals(e.g., RF signals) from the external programming unit 406. The externalprogramming unit 406 can be a home station or unit at a clinician'soffice or any other suitable device. In some embodiments, the externalprogramming unit 406 can be a device that is worn on the skin of theuser or can be carried by the user and can have a form similar to apager, cellular phone, or remote control, if desired. The externalprogramming unit 406 can be any unit that can provide information to thecontrol module 402. One example of a suitable external programming unit406 is a computer operated by the user or clinician to send signals tothe control module 402. Another example is a mobile device or anapplication on a mobile device that can send signals to the controlmodule 402

The signals sent to the processor 410 via the antenna 412 can be used tomodify or otherwise direct the operation of the electrical stimulationsystem. For example, the signals may be used to modify the pulses of theelectrical stimulation system such as modifying one or more of pulseduration, pulse frequency, pulse waveform, and pulse strength. Thesignals may also direct the control module 402 to cease operation, tostart operation, to start charging the battery, or to stop charging thebattery.

Optionally, the control module 402 may include a transmitter (not shown)coupled to the processor 410 and the antenna 412 for transmittingsignals back to the external programming unit 406 or another unitcapable of receiving the signals. For example, the control module 402may transmit signals indicating whether the control module 402 isoperating properly or not or indicating when the battery needs to becharged or the level of charge remaining in the battery. The processor410 may also be capable of transmitting information about the pulsecharacteristics so that a user or clinician can determine or verify thecharacteristics.

Any suitable memory 416, 452 can be used for the respective componentsof the system 400. The memory 416 illustrates a type ofcomputer-readable media, namely computer-readable storage media.Computer-readable storage media may include, but is not limited to,nonvolatile, removable, and non-removable media implemented in anymethod or technology for storage of information, such as computerreadable instructions, data structures, program modules, or other data.Examples of computer-readable storage media include RAM, ROM, EEPROM,flash memory, or other memory technology, CD-ROM, digital versatiledisks (“DVD”) or other optical storage, magnetic cassettes, magnetictape, magnetic disk storage or other magnetic storage devices, or anyother medium which can be used to store the desired information andwhich can be accessed by a computing device.

Communication methods provide another type of computer readable media;namely communication media. Communication media typically embodiescomputer-readable instructions, data structures, program modules, orother data in a modulated data signal such as a carrier wave, datasignal, or other transport mechanism and include any informationdelivery media. The terms “modulated data signal,” and “carrier-wavesignal” includes a signal that has one or more of its characteristicsset or changed in such a manner as to encode information, instructions,data, and the like, in the signal. By way of example, communicationmedia includes wired media such as twisted pair, coaxial cable, fiberoptics, wave guides, and other wired media and wireless media such asacoustic, RF, infrared, and other wireless media.

The user interface 456 of the external programming unit 406 can be, forexample, a keyboard, mouse, touch screen, track ball, joystick, voicerecognition system, or any combination thereof, and the like.

FIG. 6 is a flowchart of one embodiment of a method of adjustingstimulation parameters. In step 602, a biosignal is obtained. Examplesof suitable biosignals include, but are not limited to, EEG,electrocochleograph (ECOG), heart rate, ECG, blood pressure, electricalsignals traversing the spinal cord or a nerve or group of nerves, andthe like. In some embodiments, more than one biosignal can be obtainedor biosignals from two or more locations on the body of the patient canbe obtained.

In step 604, one or more stimulation parameters are adjusted based onthe obtained biosignal. Examples of stimulation parameters that can beadjusted include, but are not limited to, pulse frequency, pulse width,electrode selection (which may can also affect the location ofstimulation), pulse amplitude, and the like. The size, intensity, andcharacter of the stimulation may be controlled by adjusting thestimulation parameters (e.g., amplitude, frequency, impedance, voltage,pulse width, or the like) of the electrical stimulation signals. Theadjustment can be manual or automatic. In at least some embodiments, theadjustment is part of a programming session and the adjustment may beperformed using an external programming unit, a control module, or anyother suitable device, or any combination thereof. In at least someembodiments, the adjustment is part of the operation of the electricalstimulation system outside of the programming session and may occur at aregular or irregular interval or when requested by a user or otherindividual. The adjustment may be performed using a control module orany other suitable device, or any combination thereof.

In step 606, an electrical stimulation signal is generated and deliveredby the control module using the adjusted stimulation parameter orparameters.

FIG. 7 is a flowchart of another embodiment of a method of adjustingstimulation parameters. In step 702, a biosignal is obtained and in step704 a power spectrum of the biosignal is determined. The power spectrummay be determined by, for example, an external programming unit, acontrol module, or any other suitable device. In step 706, one or morestimulation parameters are adjusted based on the power spectrum.Examples of stimulation parameters that can be adjusted include, but arenot limited to, pulse frequency, pulse width, electrode selection (whichmay can also affect the location of stimulation), pulse amplitude, andthe like. The size, intensity, and character of the stimulation may becontrolled by adjusting the stimulation parameters (e.g., amplitude,frequency, impedance, voltage, pulse width, or the like) of theelectrical stimulation signals. The adjustment can be manual orautomatic. In at least some embodiments, the adjustment is part of aprogramming session and the adjustment may be performed using anexternal programming unit, a control module, or any other suitabledevice, or any combination thereof. In at least some embodiments, theadjustment is part of the operation of the electrical stimulation systemoutside of the programming session and may occur at a regular orirregular interval or when requested by a user or other individual. Theadjustment may be performed using a control module or any other suitabledevice, or any combination thereof. In step 708, an electricalstimulation signal is generated and delivered by the control moduleusing the adjusted stimulation parameter or parameters.

FIG. 8 is a flowchart of another embodiment of a method of adjustingstimulation parameters. In step 802, two or more biosignals are obtainedat different portion of the patient's body. In step 804, coherence,correlation, or other measure of association between the biosignals isdetermined. The coherence, correlation, or other measure of associationmay be determined by, for example, an external programming unit, acontrol module, or any other suitable device. In step 806, one or morestimulation parameters are adjusted based on the coherence, correlation,or other measure of association between the biosignals. Examples ofstimulation parameters that can be adjusted include, but are not limitedto, pulse frequency, pulse width, electrode selection (which may canalso affect the location of stimulation), pulse amplitude, and the like.The size, intensity, and character of the stimulation may be controlledby adjusting the stimulation parameters (e.g., amplitude, frequency,impedance, voltage, pulse width, or the like) of the electricalstimulation signals. The adjustment can be manual or automatic. In atleast some embodiments, the adjustment is part of a programming sessionand the adjustment may be performed using an external programming unit,a control module, or any other suitable device, or any combinationthereof. In at least some embodiments, the adjustment is part of theoperation of the electrical stimulation system outside of theprogramming session and may occur at a regular or irregular interval orwhen requested by a user or other individual. The adjustment may beperformed using a control module or any other suitable device, or anycombination thereof. In step 808, an electrical stimulation signal isgenerated and delivered by the control module using the adjustedstimulation parameter or parameters.

FIG. 9 is a flowchart of another embodiment of a method of adjustingstimulation parameters. In step 902, a biosignal is obtained.Optionally, a power spectrum can be determined from the biosignal, asdescribed above with respect to the method illustrated in FIG. 7.Alternatively or additionally, two or more biosignals can be obtainedand a coherence, correlation, or other measure of association betweenthe biosignals can be determined, as described above with respect to themethod illustrated in FIG. 8.

In step 904, one or more stimulation parameters are adjusted based onthe power spectrum. Examples of stimulation parameters that can beadjusted include, but are not limited to, pulse frequency, pulse width,electrode selection (which may can also affect the location ofstimulation), pulse amplitude, and the like. The size, intensity, andcharacter of the stimulation may be controlled by adjusting thestimulation parameters (e.g., amplitude, frequency, impedance, voltage,pulse width, or the like) of the electrical stimulation signals. Theadjustment can be manual or automatic. In at least some embodiments, theadjustment is part of a programming session and the adjustment may beperformed using an external programming unit, a control module, or anyother suitable device, or any combination thereof. In at least someembodiments, the adjustment is part of the operation of the electricalstimulation system outside of the programming session and may occur at aregular or irregular interval or when requested by a user or otherindividual. The adjustment may be performed using a control module orany other suitable device, or any combination thereof.

In step 906, an electrical stimulation signal is generated and deliveredby the control module using the adjusted stimulation parameter orparameters. In step 908, the effect of the electrical stimulation signalcan be determined. In at least some embodiments, the effect isdetermined by measuring a biosignal. In step 910, the system or a usercan decide whether to repeat the procedure to further adjust thestimulation parameters. If the decision is to repeat, then steps 902-908can be repeated as illustrate in FIG. 9. If the effect of thestimulation was determined using a biosignal that biosignal may be usedin step 902.

This process can be used as a feedback loop to adjust stimulationparameters. The feedback loop may be part of a programming session.Alternatively or additionally, the electrical stimulation system mayinitiate the feedback loop on a regular or irregular basis or whenrequested by a user, clinician, or other individual to adjuststimulation parameters.

It will be understood that the system can include one or more of themethods described hereinabove with respect to FIGS. 6-9 in anycombination. The methods, systems, and units described herein may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein. Accordingly, the methods, systems,and units described herein may take the form of an entirely hardwareembodiment, an entirely software embodiment or an embodiment combiningsoftware and hardware aspects. The methods described herein can beperformed using any type of processor or any combination of processorswhere each processor performs at least part of the process.

It will be understood that each block of the flowchart illustrations,and combinations of blocks in the flowchart illustrations and methodsdisclosed herein, can be implemented by computer program instructions.These program instructions may be provided to a processor to produce amachine, such that the instructions, which execute on the processor,create means for implementing the actions specified in the flowchartblock or blocks or described for the control modules, externalprogramming units, sensors, systems and methods disclosed herein. Thecomputer program instructions may be executed by a processor to cause aseries of operational steps to be performed by the processor to producea computer implemented process. The computer program instructions mayalso cause at least some of the operational steps to be performed inparallel. Moreover, some of the steps may also be performed across morethan one processor, such as might arise in a multi-processor computersystem. In addition, one or more processes may also be performedconcurrently with other processes, or even in a different sequence thanillustrated without departing from the scope or spirit of the invention.

The computer program instructions can be stored on any suitablecomputer-readable medium including, but not limited to, RAM, ROM,EEPROM, flash memory or other memory technology, CD-ROM, digitalversatile disks (“DVD”) or other optical storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,or any other medium which can be used to store the desired informationand which can be accessed by a computing device.

The above specification, examples and data provide a description of themanufacture and use of the composition of the invention. Since manyembodiments of the invention can be made without departing from thespirit and scope of the invention, the invention also resides in theclaims hereinafter appended.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A method of adjusting stimulation parameters ofan electrical stimulation system including a control module implanted ina patient, the method comprising: obtaining a biosignal of the patient;analyzing the biosignal to determine whether the biosignal is indicativeof pain; and altering at least one stimulation parameter of theelectrical stimulation system in response to the biosignal when thebiosignal is indicative of pain.
 2. The method of claim 1, furthercomprising delivering electrical stimulation signals from the controlmodule to one or more selected electrodes of the electrical stimulationsystem using the at least one stimulation parameter.
 3. The method ofclaim 1, further comprising communicating the at least one stimulationparameter to the control module.
 4. The method of claim 1, furthercomprising determining a power spectrum from the biosignal, whereinaltering the at least one stimulation parameter comprises altering theat least one stimulation parameter of the electrical stimulation systemin response to the power spectrum.
 5. A method of adjusting stimulationparameters of an electrical stimulation system including a controlmodule implanted in a patient, the method comprising: obtaining at leasttwo different biosignals of the patient, determining a measure ofassociation between the at least two different biosignals, and alteringat least one stimulation parameter of the electrical stimulation systemin response to the measure of association between the at least twodifferent biosignals.
 6. The method of claim 5, further comprisingdelivering electrical stimulation signals from the control module to oneor more selected electrodes of the electrical stimulation system usingthe at least one stimulation parameter.
 7. The method of claim 5,wherein determining the measure of association comprises determining ameasure of coherence between the at least two different biosignals. 8.The method of claim 5, wherein determining the measure of associationcomprises determining a measure of correlation between the at least twodifferent biosignals.
 9. The method of claim 5, wherein obtaining the atleast two different biosignals of the patient comprises obtaining anelectroencephalogram of a theta band for the patient and anelectroencephalogram of a gamma band for the patient.
 10. The method ofclaim 5, wherein obtaining the at least two different biosignals of thepatient comprises obtaining a same type of biosignal at two differentpoints in time.
 11. The method of claim 5, wherein obtaining the atleast two different biosignals of the patient comprises obtaining a sametype of biosignal at two different locations on a body of the patient.12. The method of claim 5, wherein determining the measure ofassociation comprises determining the measure of association between theat least two different biosignals to determine whether the measure ofassociation is indicative of synchronous activity.
 13. The method ofclaim 5, wherein determining the measure of association comprisesdetermining the measure of association between the at least twodifferent biosignals to determine whether the measure of association isindicative of pain.
 14. The method of claim 5, further comprisingdelivering the electrical stimulation signals to a plurality of selectedelectrodes of the electrical stimulation system using the at least onestimulation parameter to produce stimulation to at least two differentstimulation sites.
 15. A method of adjusting stimulation parameters ofan electrical stimulation system including a control module implanted ina patient, the method comprising: obtaining a biosignal of the patient;determining a power spectrum from the biosignal; and altering at leastone stimulation parameter of the electrical stimulation system inresponse to the power spectrum.
 16. The method of claim 15, furthercomprising delivering electrical stimulation signals from the controlmodule to one or more selected electrodes of the electrical stimulationsystem using the at least one stimulation parameter.
 17. The method ofclaim 15, wherein determining the power spectrum comprises obtaining aFourier transformation of the biosignal.
 18. The method of claim 15,wherein determining the power spectrum comprises determining the powerspectrum of the biosignal to determine whether the power spectrum isindicative of pain.
 19. The method of claim 15, wherein determining thepower spectrum comprises determining the power spectrum of thebiosignal, wherein the biosignal comprises a theta band in a range of 4to 8 Hz.
 20. The method of claim 15, further comprising communicatingthe at least one stimulation parameter to the control module.